commit: add support for signed commits

Add a `sign` flag to the Commit command.

Add a "Create Signed Commit" checkbox to the commit message editor so
that signed commits can be toggled on/off.

Default the checkbox to:

	git config --bool cola.signcommits

This allows us to enable this feature by default by setting:

	git config cola.signcommits true

Closes #149

Suggested-by: Justin Lecher <jlec@gentoo.org>
Cheered-on-by: Micha Rosenbaum <micha@rosetree.de>
Signed-off-by: David Aguilar <davvid@gmail.com>

cola/cmds.py

@@ -344,10 +344,11 @@ class Commit(ResetMode):
 
     SHORTCUT = 'Ctrl+Return'
 
-    def __init__(self, amend, msg):
+    def __init__(self, amend, msg, sign):
         ResetMode.__init__(self)
         self.amend = amend
         self.msg = msg
+        self.sign = sign
         self.old_commitmsg = self.model.commitmsg
         self.new_commitmsg = ''
 
@@ -358,7 +359,9 @@ def do(self):
         core.write(tmpfile, msg)
 
         # Run 'git commit'
-        status, out, err = self.model.git.commit(F=tmpfile, v=True,
+        status, out, err = self.model.git.commit(F=tmpfile,
+                                                 v=True,
+                                                 gpg_sign=self.sign,
                                                  amend=self.amend)
         core.unlink(tmpfile)
 

cola/widgets/commitmsg.py

@@ -93,6 +93,13 @@ def __init__(self, model, parent):
         self.amend_action.setShortcut(cmds.AmendMode.SHORTCUT)
         self.amend_action.setShortcutContext(Qt.ApplicationShortcut)
 
+        # Sign commits
+        cfg = gitcfg.current()
+        self.sign_action = self.actions_menu.addAction(
+                N_('Create Signed Commit'))
+        self.sign_action.setCheckable(True)
+        self.sign_action.setChecked(cfg.get('cola.signcommits', False))
+
         # Spell checker
         self.check_spelling_action = self.actions_menu.addAction(
                 N_('Check Spelling'))
@@ -430,7 +437,8 @@ def commit(self):
                         N_('Amend Commit'),
                         default=False, icon=save_icon())):
             return
-        status, out, err = cmds.do(cmds.Commit, amend, msg)
+        sign = self.sign_action.isChecked()
+        status, out, err = cmds.do(cmds.Commit, amend, msg, sign)
         if status != 0:
             Interaction.critical(N_('Commit failed'),
                                  N_('"git commit" returned exit code %s') %

share/doc/git-cola/git-cola.rst

@@ -330,6 +330,15 @@ into the commit message editor when this option is selected.
 
 The `Status` tool will display all of the changes for the amended commit.
 
+Create Signed Commit
+--------------------
+Tell `git commit` to use GPG to sign commits.
+Using this option is equivalent to passing the ``-S`` option
+to `git commit <http://git-scm.com/docs/git-commit>`_.
+
+This option's default value can be configured using the `cola.signcommits`
+configuration variable.
+
 APPLY PATCHES
 =============
 Use the ``File -> Apply Patches`` menu item to begin applying patches.
@@ -408,6 +417,11 @@ cola.readsize
 The maximum size to read is controlled by `cola.readsize`
 and defaults to `2048`.
 
+cola.signcommits
+----------------
+`git cola` will sign commits using `git commit -S` by default when set `true`.
+See the section below on setting up GPG for more details.
+
 gui.diffcontext
 ---------------
 The number of diff context lines to display.
@@ -555,6 +569,55 @@ Specifies the general prompt string to display at the top of the dialog,
 before subsections for argprompt and revprompt.
 The default value includes the actual command.
 
+SETTING UP GPG FOR SIGNED COMMITS
+=================================
+When creating signed commits `gpg` will attempt to read your password from the
+terminal from which `git cola` was launched.
+The way to make this work smoothly is to use a GPG agent so that you can avoid
+needing to re-enter your password every time you commit.
+
+This also gets you a graphical passphrase prompt instead of getting prompted
+for your password in the terminal.
+
+Install gpg-agent and friends
+-----------------------------
+On Mac OS X, you may need to `brew install gpg-agent` and install the
+`Mac GPG Suite <https://gpgtools.org/macgpg2/>`_.
+
+On Linux use your package manager to install gnupg-agent and pinentry-qt4, e.g.::
+
+    sudo apt-get install gnupg-agent pinentry-qt4
+
+Configure gpg-agent and a pin-entry program
+-------------------------------------------
+Edit `~/.gnupg/gpg.conf` to include the line,::
+
+    use-agent
+
+Edit `~/.gnupg/gpg-agent.conf` to contain a pinentry-program line pointing to
+the pin-entry program for your platform.
+
+The following example `gpg-agent.conf` shows how to use pinentry-qt4 on Linux::
+
+    pinentry-program /usr/bin/pinentry-qt4
+    default-cache-ttl 3600
+    enable-ssh-support
+    use-standard-socket
+
+This following example `gpg-agent.conf` shows how to use MacGPG2's
+pinentry app on On Mac OS X::
+
+    pinentry-program /usr/local/MacGPG2/libexec/pinentry-mac.app/Contents/MacOS/pinentry-mac
+    default-cache-ttl 3600
+    enable-ssh-support
+    use-standard-socket
+
+Once this has been setup then you will need to eval the output
+of `gpg-agent --daemon` in your shell prior to launching git-cola.::
+
+    eval $(gpg-agent --daemon)
+    bin/git-cola
+
 LINKS
 =====
 

share/doc/git-cola/thanks.rst

@@ -51,6 +51,7 @@ Thanks
 * Maarten Nieber
 * Matěj Šmíd
 * Matthew Levine
+* Micha Rosenbaum
 * Michael Geddes
 * Michael Homer
 * Minarto Margoliono